sequenceR (version 1.0.1)

envelope: Envelope constructor.

Description

Creates a new instance of an 'envelope' object (https://en.wikipedia.org/wiki/Envelope_(music)). In this package an envelop is viewed as a curve v(t), where t is the time and v the value of the envelope. Time t is normalized between 0 and 1 so that 1 corresponds to the end of the sound sample the envelope is applied to (and 0 to its beginning). The curve is defined by a discrete set of points (t,v) (linear interpolation in between).

Usage

envelope(t, v)

Value

An object of class 'envelope'.

Arguments

t

Numeric vector, normalized time. Vector of increasing values starting at 0 and ending at 1.

v

Numeric vector, same size as t, envelop values v(t).

Examples

# A triangular envelop
env <- envelope(t=c(0,0.3,1),v=c(0,1,0))
# An ADSR envelope (https://en.wikipedia.org/wiki/Envelope_(music)#ADSR)
env <- envelope(t=c(0,0.1,0.3,0.8,1),v=c(0,1,0.4,0.4,0))
# An envelope that could be used for a 1-octave frequency modulation (from 440 to 220 Hz)
env <- envelope(t=c(0,1),v=c(440,220))
# An envelope that could be used for phase modulation
# (https://en.wikipedia.org/wiki/Phase_modulation)
env <- envelope(t=seq(0,1,0.01),v=(-pi/2)*sin(2*pi*4*seq(0,1,0.01)))